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CONTINUOUS redox processes have been effected between aqueous reactants, separated by liquid membranes in which coenzyme Q, or vitamin K, is present as a carrier molecule. These membranes show chemical specificity and function which relate closely to certain biological electron transfer processes.

Under the influence of an electric field, vesicles in suspension partially deform or orientate, rendering the medium optically birefringent. The amplitudes of the birefringence under fields of variable amplitude lead to evaluation of the anisotropy of the electrical delta alpha and optical delta G polarisabilities of the vesicles. By using pulsed fields, rates of establishment and decay of birefringence enable vesicle sizes d to be measured. Samples of 9:1 phosphatidylcholine-phosphatidylserine liposome suspension in water were studied in the presence of various additives, including sucrose, an antibiotic (streptomycin), a steroid (dexamethasone), an anaesthetic (lignocaine) and a fluidising agent (benzyl alcohol). The changes in the three parameters delta alpha, delta G and d were different for each additive and are thought to be indicative of the mode of interaction of each. Electric birefringence also appears to be a rapid means of detecting structure changes.

Glycophorin from human erythrocytes has been incorporated into liposomes of dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC). The thermal properties of unsonicated liposomes with glycophorin/lipid molar ratios up to 4.10(-3) have been studied by differential scanning calorimetry and the numbers of lipids withdrawn from participation in the gel-to-lamellar phase transition were found to be 42 +/- 22 (DMPC), 197 +/- 28 (DPPC) and 240 +/- 64 (DSPC). The initial rates of agglutination of sonicated liposomes with glycophorin/lipid molar ratios up to 4.10(-3) by wheat germ agglutinin in the concentration range 0-7 microM have been measured over a range of temperature. Below the gel-to-lamellar phase transition (Tc) the rates of agglutination increase with acyl chain length in the sequence DMPC less than DPPC less than DSPC. Agglutination is found to be second order in liposome concentration and is completely reversed on saturation of the wheat germ agglutinin-binding sites by N-acetylglucosamine. Agglutination rates decrease with increasing temperature below Tc and are largely independent of temperature above Tc. The results are discussed in relation to the clustering of glycophorin in the phospholipid bilayers and its effect on binding and subsequent interliposomal bridge formation by wheat germ agglutinin.